Outcomes of Lower Limb Osseointegration: A Six-Year Experience at the Montreal Oi Clinic

The study aims to evaluate clinical outcomes including functional improvements, implant survival, and complications investigate. We also inquired about the durability and sustainability of osseointegration and assess it's impact on patients. The study involves the analysis of the prospectively collected Montreal Osteointegration (OI) Clinic's Redcap database between March 2018 and April 2024. All provided informed consent and IRB authorization was given. The study includes patients with a minimum of six months of follow-up and involves data collection on various clinical parameters, including complications, and functional tests (2MWT, 6MWT, AMPPRO and TUG). There were 58 patients (59 implantation). Thirty-five underwent standard femur OI, five underwent short femur OI with custom locked implants and 18 underwent tibial OI, all with custom locked implants. Among the tibial OIs there is a patient with bilateral below knee amputation that got OI in the same setting. Follow up averaged 2.6 years (0.6-6.2 yrs). Age averaged 36 yrs at amputation (12-66 yrs) and 54 yrs at osseointegration (30-77yrs). Fractures during implant insertion occurred in 13 patients (22.3%); eight fractures occurred in femurs (including 2 in short femurs) and five in tibias. Five fractures were managed with cerclage wires while the others did not require additional management. Infections were categorized according to Al Muderis proposed classification. A total of 18 patients developed at least one post-operative infection (31%): 3 patients were Gr 2 (two 2 b and one 2 c). Three ultimately developed radiographical evidence of chronic femur osteomyelitis but doing well under chronic suppressive oral antibiotics (3 a). All the others were Gr 1a. Two patients experienced femur fractures after falling. One was intertrochanteric and did well after ORIF. The other was a greater trochanter undisplaced fracture was successfully managed conservatively. None of the OI implants failed or were revised. One wheelchair bounded case of congenital absence of pain with bilateral tibial OI sustained Charcot's bilateral tibial plateau fractures at 1 yr and managed with TKAs. One year later, while ambulating without aids at that time, he died unexpectedly from unidentified cause. The functional assessment conducted on patients at the 2-year mark yielded the following results: 2-Minute Walk Test (2MWT):): Pre OI minimum-maximum 0 - 170; 2 years post-OI minimum-maximum 89 - 180, with the mean 114.2 to 135.07 (P =0.0003). 6-Minute Walk Test (6MWT): Pre OI minimum-maximum 0 - 495; 2 years post-OI minimum-maximum 210 - 514, with the mean 292.82 to 400.1 (P = 0. 0.00001). AMPPRO: Pre OI minimum-maximum 34 - 46, mean; 2 years post-OI minimum-maximum 38 - 46, with the mean 42.48 to 43.55 (P = 0.008). Timed Up and Go Test (TUG): Pre OI minimum-maximum 0-29; 2 years post-OI minimum-maximum 6.78-22.02, with the mean decreasing from 12.24 to 10.52 (p = 0.092). Our study supports osseointegration as a viable and beneficial procedure and contributes valuable insights for lower limb amputees doing poorly with socket prosthesis. We found no difference among the different level of amputation. It did improve function and most complication were manageable without implant revision or removal. Albeit frequent, infection remained minor in most. Chronic osteomyelitis could be managed so far with chronic oral antibiotic suppression.